This application describes an integrated 5-year training program to develop the candidate into an independent investigator in the area of treatment intervention in young children with psychiatric and developmental disorders. Primary mentorship will be provided by Mark Riddle, M.D., an accomplished researcher in the field of pediatric psychopharmacology who has extensive experience training young investigators. Additional mentorship and consultation will be provided by experts, most of whom work in a collaborative environment with the candidate and her primary mentor; each will provide training in a specialized area of expertise critical to the candidate's development. A focused didactic program of formal course work, training, guided study, structured mentored relationship, empirical research, and other career development activities is proposed in several areas relevant to the candidate's short-and long-term goals. The majority of the formal coursework and training will occur at the Johns Hopkins School of Hygiene and Public Health and School of Medicine. The following objectives will be achieved: 1) develop conceptual and methodological understanding of clinical interventions research; 2) design and implement a methylphenidate (MPH) outcome study for the treatment of symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in young children with PDD (Autistic Disorder, Asperger's Disorder and Pervasive Developmental Disorder Not Otherwise Specified); 3) evaluate, analyze, integrate, and interpret data from this study; 4) disseminate results from this research; and 5) develop R01 treatment intervention research application. The primary research vehicle for achieving these objectives involves a research project to study short-term safety and efficacy of MPH in young children with PDD along with symptoms of ADHD. The specific aim of the study is to test the hypothesis that MPH is an effective and safe treatment for the symptoms of ADHD in young children with PDD. A secondary aim of the study is to examine feasibility and treatment-sensitivity of neuropsychological measures for the implicated domains of executive function in ADHD. The proposed study is the beginning of a larger investigation aimed at identifying and developing safe, effective and better treatments for young children with psychiatric and developmental disorders. The proposed training program will allow the candidate to acquire sufficient expertise to carry out future treatment intervention studies in a very specialized area.